2008 iMac slow on Internet

Discussion in 'iMac' started by Tusenstammar, Oct 6, 2011.

  1. Tusenstammar macrumors newbie

    Oct 6, 2011
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    So I have a 2008 iMac (3,06Ghz, 4Gb ,500Gb) and for the past year its been terribly slow when it comes to surfing online. This may sound like a trivial complaint but it's really frustrating.

    Quick overview of the problem and what I've tried:
    - Really its not so much slow but rather that nothing happens for a long time and then maybe it loads the site or maybe it doesn't
    - I've clocked 140Mb down on speedtest.net, so it shouldn't be my connection
    - I also have an Acer 5920 laptop (even older than the iMac, 2007 or so).. It has no Problems loading several sites/tabs at the same time, and theres none of the "nothing happening, maybe it will work" that I have with the iMac. If its slow then it just loads slow, but something is still happening
    - I've tried connecting the iMac directly to my Thomson router/modem with a cat5e ethernet cable. > No noticable difference (The PC became even faster)

    - I've tried swithing the router to operate on 5Ghz from 2,4 Ghz> no noticable difference

    - I've tried hooking up a A-Link b/g/n router that claims to do 300mb/s to the Thomson modem/router and connecting through it instead > no noticable difference

    - My iPhone loads sites faster and more reliably than the iMac

    - I've tried safari, firefox and google chrome.. No difference

    All this leads me to believe there must be something wrong with my iMac, even though it still runs even demanding programs smoothly and I have no problems downloading something at my subsciptions max speed. The "slowness" only pertains to surfing, especially if I have several tabs open at the same time.

    I have two theories:
    #1: theres some sort of bottle neck that doesnt like "separate streams of data"(?)

    #2: I only have about 20gb left of HD space, could this slow down the iMac? But then why is everything else running smoothly?

    Any input would be much appreciated, I just spent the past 5 hours moving it close to the modem and testing different alternatives

    (written with my iPhone, sure to contain some grammar mistakes)
  2. Tusenstammar thread starter macrumors newbie

    Oct 6, 2011
    Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_3_1 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8G4 Safari/6533.18.5)

    Ohyeah, OS 10.6.8
  3. Tusenstammar thread starter macrumors newbie

    Oct 6, 2011
  4. tom vilsack macrumors 68000

    tom vilsack

    Nov 20, 2010
    ladner cdn
    try this....http://code.google.com/speed/public-dns/docs/using.html

    use these For IPv4: and/or

    Mac OS X

    DNS settings are specified in the Network window.

    Example: Changing DNS server settings on Mac OS 10.5

    From the Apple menu, click System Preferences, then click Network.
    If the lock icon in the lower left-hand corner of the window is locked, click the icon to make changes, and when prompted to authenticate, enter your password.
    Select the connection for which you want to configure Google Public DNS. For example:
    To change the settings for an Ethernet connection, select Built-In Ethernet, and click Advanced.
    To change the settings for a wireless connection, select Airport, and click Advanced.
    Select the DNS tab.
    Click + to replace any listed addresses with, or add, the Google IP addresses at the top of the list:
    For IPv4: and/or
    For IPv6: 2001:4860:4860::8888 and/or 2001:4860:4860::8844
    Click Apply and OK.
    Test that your setup is working correctly; see Testing your new settings below.
    Repeat the procedure for additional network connections you want to chang
  5. Spike88, Oct 6, 2011
    Last edited: Oct 6, 2011

    Spike88 macrumors 6502a

    Jan 25, 2010
    My iMac "out of the box" has (had) slow internet connectivity as well. After several hours of surfing, I had to apply the following "fixes":

    - Change from DHCP to Fixed (static) IP Address. My DSL modem comes with 5 static IPs. I use one of them within my iMac.
    - For my "wire" connection, I changed from auto/auto to FULL - 100 MBPS. Was told some (not all) attached devices have problems synchronizing with auto-auto. Especially different vender devices. With fixed speed and fixed duplex, its more stable. If wire connection, I'd recommend fixed-fixed values as well.
    - Manually change to fixed DNS addresses. See above posts.
    - Manually "turn off" IPV6. This change helped improve speed as well. Especially since my iMac is behind a IPv4 DSL Modem.
    - Manually change the iMac's MTU value. My DSL model / iMac box seems to work best with fixed (static) value of 1492. For more details, surf: http://hints.macworld.com/article.php?story=20020712014842725 If wondering, this custom MTU setting made the biggest speed improvement.
    - If wireless, I hear that some (not all) iMacs have problems with WEP authentication as well. Change to WPA or WPA2 encryption. This advanced wireless encryption is more secure then WEP anyway.
    - If your DSL/Internet Gateway devices uses its own firewall (most do these days), then disabled (turn off) the software Firewall feature within your iMac. If Internet connection is more stable or faster, one found the problem. re: Both firewalls are fighting / blocking with one another. If turning off iMac's internal firewall did NOT make a speed improveemnt difference, then turn the iMac's internal Firewall back on. Having double firewalls (internet access device and internal iMac) is more benefitial then only 1 firewall.

    These are the things I had to change / tweak within my iMac box. Its internet access isn't as fast as my HP laptop but its much more faster - compared to its "pure stock" iMac box.

    Hope these items help as well...

  6. Spike88 macrumors 6502a

    Jan 25, 2010
  7. Tusenstammar thread starter macrumors newbie

    Oct 6, 2011
    Where can I see the IP addresses that I need to change it to? Within the modems (it's a cable modem/router) system settings, or?

    I tried your speed test (3 times on both computers). iMac got 1.2, 1.3 and 1.3 and and my (Vista) PC got 1.3, 1.4, 0.784.. The PC seemed to vary more. :)

    Right after I did that test i tried the www.speedtest.net again and got around 99Mbps on both.
  8. Spike88 macrumors 6502a

    Jan 25, 2010
    For iMac changes:
    - surf Applications - Systems Preferences - Personal - Security - Firewall panels.
    - Surf Applications - Systems Preference - Internet & Wireless - Network panels.

    If uncomfortable within these iMac panels, best to ask Apple Store specialist to investigate / change these settings for you.

    For Interent Gateway (re: Cable Modem) changes, its best to ask your ISP (Internet Service Provider) Tech Support for help. Or, surf their Web page with a different computer and obtain how they recommend setting your Cable Modem. And, setting their recommend for attached Apple devices.

    Good luck...
  9. AndyMoore macrumors 6502


    Feb 8, 2008

    If it's just web browsing that's slow and your other tests like ping are fine, then you should try Tom's suggestion above as is certainly sounds like a DNS issue.

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